Because they've never met or spoke with a scientist.

Came across this art installation, Liza Lou's Kitchen, at the Whitney Museum of American Art, NYC. It's a kitchen made of tiny glass beads, that artist Liza Lou did, taking 5 yrs. to complete, from 1991 - 1996.

My favorite part is the sink.

Take a moment and ask yourself, a project like this requires a lot of time, money and dedication of resources, why would scientists dedicate that time to something that could just be done by a tree?

The answer is they wouldn't. So that means this claim requires further investigation!

This project is called LIQUID 3, and it's not meant for cities with wide open spaces, it's meant for cities like Belgrade in Serbia. These cities are densely populated and heavily polluted, to the point where pollution actually chokes out current trees and makes creating green spaces difficult.

Liquid 3 was a PhD scientists answer to these problems. The microalgae tank is intended for spaces where you either:

Don't have enough space to plant full trees, or

Don't have enough time to plant trees and wait for them to grow up.

The tank is extremely efficient when you consider the amount of space needed compared to the amount of CO2 turned into oxygen. The tank can operate throughout the winter. And most importantly, it can be quickly set up in areas that desperately need relief from air pollution NOW not in 10 years when trees are done growing. Children currently suffocating on polluted air can't wait for trees to grow, they need to be taken care of now, and Liquid 3 is one of the ways to take care of them. Depending on the species of microalgea used, a number have shown a pretty amazing capacity to pull heavy metals out of the air which is something trees can get choked up by.

The tanks aren't just tanks either! Liquid 3 have solar panels placed on top, they have lighting and mobile phone charging, and they work as public benches. The designers of it want to encourage green spaces where there's room, but where there isn't room or time, Liquid 3 can step in. Realistically, this isn't a replacement for trees. It's replacing boring metal city benches with new, cooler benches that also clean the air (and have at least some heating during the winter).

Not only that, but the microalgea that grows is native to Serbia and all that microalgea has a ton of great uses! It makes for great fertilizer, compost, wastewater treatment, cleaner biofuels and even for helping create new tanks for further air purification. They only require a quick algae divide once a month, and the produced algae can be carted off to where ever it's needed. This makes them effective solutions for areas that can't sustain complex installations.